Lysozyme is a highly active enzyme which was originally isolated by Fleming during his early work on penicillin. Lysozyme is found in mammalian, including human, tissues and body fluids such as blood, tears, and milk as well as in avian sources, such as avian egg-white and vegetable sources. It is also found in bacteria and bacteriophages. The major sources of lysozyme to date has been avian eggs and various methods are known for the isolation thereof in reasonable degrees of purity. These procedures however are lengthy, tedious, and expensive and do not lend themselves readily to production scale isolation of lysozyme. Lysozyme from avian sources may be used as a food preservative. It has long been considered a highly desirable preservative since it may be passed into the human digestive system with no adverse effects thereto and does not suffer from the problem of chemical residue which effects many artificial preservatives. Unfortunately however the cost factor heretofore involved in producing large amounts of pure lysozyme have, in effect, prevented its large scale utilization for this highly desirable purpose.
Since lysozyme operates as a bacteriolytic agent it is of potential use as a potentiator for drugs such as antibiotics and the like. Unfortunately, heretofore there have been certain immunological barriers to its use for this purpose. While avian and non-human lysozyme may be ingested by humans without adverse immunological effects non-human lysozyme will set up antibody reactions when ininjected into the human circulatory system. When lysozyme from human sources is injected into the human circulatory system antibody response is sometimes obtained and sometimes not obtained. The only way of ensuring absolutely that no antibody response would be obtained would be to inject lysozyme obtained from the injected subject itself together with the desired drug. Thus, it would be desirable to develop a method for efficiently separating lysozyme from a human subject in such a way that the supplying constituents of that subject are not otherwise degraded. Similarly, since there are known tests for antibody response, if human lysozyme can be readily obtained from other human sources, it is a comparatively simple job of testing to determine whether or not a subject would exhibit antibody response if foreign human lysozyme were injected into that human system.
Heretofore the available methods of isolating lysozyme from human sources have not been sufficiently efficient either to supply an adequate amount of lysozyme in sufficient purity to ensure that no antibody response due to other protein sources would be invoked, or, the methods available for the supply of pure lysozyme have been so expensive as to be worthless from a practical, that is to say, nonacademic point of view.
Chitin is a known material which may be obtained from various marine sources such as crabs and the like. Chitin from crabs has been utilized in procedures for the isolation, but not purification, of lysozyme.